Stamping method and stamping apparatus

ABSTRACT

A stamping method includes: punching out a product from a workpiece by using a die on which the conveyed workpiece is placed, a punch, and a back pressure portion; displacing the workpiece upward with respect to the die when the punch moves away from the die; before the product is punched out, providing a protrusion that protrudes downward and is located at a part of the workpiece, the part being on the upstream side in a workpiece conveying direction of a punch-out portion and aligned with the punch-out portion; and using the protrusion, which is displaced downstream in the conveying direction together with the workpiece, to push the product downstream in the conveying direction, so that the product is ejected to the outside.

BACKGROUND 1. Field

The following description relates to a stamping method and a stampingapparatus.

2. Description of Related Art

Conventionally, fine blanking has been known as a method of punching outa product from a plate-shaped workpiece using a die and a punch. In fineblanking, a plate holding member, a die, a punch, and a back-up member,which is provided inside the die, are used. Specifically, the oppositesides of a workpiece are held by the die and the plate holding member,and a product is punched out from the workpiece using the die and thepunch while the workpiece is held from the side opposite to the punch bythe back-up member.

Japanese Laid-Open Patent Publication No. 2005-262294 discloses anapparatus that takes out a product to the outside from a fine blankingpress. The apparatus of the publication includes a nozzle for drawing inair and uses the nozzle to apply suction to the product, therebyejecting the product to the outside.

Since the apparatus of the above-described publication is required tohave a nozzle to eject the punched product, the structure of theapparatus as a whole is complicated.

SUMMARY

It is an objective of the present disclosure to provide a stampingmethod and a stamping apparatus that are capable of ejecting productsusing a simple structure.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

In a general aspect, a stamping method for punching out a product from aworkpiece that is conveyed intermittently is provided. The methodincludes: punching out the product from the workpiece by using a die onwhich the conveyed workpiece is placed, a punch that is arranged toapproach and move away from the die, and a back pressure portion that isprovided in the die and is urged toward the punch to apply a backpressure to the workpiece; displacing the workpiece upward with respectto the die when the punch moves away from the die; before the product ispunched out, providing a protrusion that protrudes downward and islocated at a part of the workpiece, wherein the part is on an upstreamside in a workpiece conveying direction of a punch-out portion, fromwhich the product is punched out, and is aligned with the punch-outportion; and using the protrusion, which is displaced downstream in theconveying direction together with the workpiece, to push the productdownstream in the conveying direction, so that the product is ejected tothe outside.

In another general aspect, a stamping apparatus for punching out aproduct from a workpiece that is conveyed intermittently is provided.The apparatus includes a punch-out mechanism, a protrusion providingmechanism, and a displacing mechanism. The punch-out mechanism includesa die on which the conveyed workpiece is placed, a punch that isarranged to approach and move away from the die, and a back pressureportion that is provided in the die and is urged toward the punch toapply a back pressure to the workpiece. The punch-out mechanism isconfigured to punch out the product from the workpiece by using the die,the punch, and the back pressure portion. The protrusion providingmechanism is configured to provide a protrusion that protrudes downwardand is located at a part of the workpiece. The part is on an upstreamside in a workpiece conveying direction of a punch-out portion, fromwhich the product is punched out, and is aligned with the punch-outportion. The displacing mechanism is configured to displace theworkpiece to a position where the protrusion and the product are alignedwith each other in the conveying direction when the punch moves awayfrom the die.

Other features and aspects will be apparent from the following detaileddescription, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a stamping method and a stampingapparatus according to one embodiment, illustrating the structure of thestamping apparatus.

FIG. 2 is a plan view of a workpiece illustrating protrusions of theembodiment together with a punch-out portion.

FIG. 3 is a cross-sectional view of the stamping method of theembodiment, illustrating a state in which the workpiece has beenconveyed to a protrusion providing mechanism.

FIG. 4 is a cross-sectional view of the stamping method of theembodiment, illustrating a state in which protrusions have been providedon the workpiece.

FIG. 5 is a cross-sectional view of the stamping method of theembodiment, illustrating a state in which the workpiece has beenconveyed to a punch-out mechanism.

FIG. 6 is a cross-sectional view of the stamping method of theembodiment, illustrating a state in which the workpiece is held by asecond lower die assembly and a second upper die assembly.

FIG. 7 is a cross-sectional view of the stamping method of theembodiment, illustrating a state in which a product has been punched outfrom the workpiece by a second punch.

FIG. 8 is a cross-sectional view of the stamping method of theembodiment, illustrating a state in which the product is lifted by aback pressure portion.

FIG. 9 is a cross-sectional view of the stamping method of theembodiment, illustrating a state in which the product is being pushedtoward an ejection portion by protrusions.

FIG. 10 is a plan view of a workpiece illustrating a protrusion of amodification together with a punch-out portion.

Throughout the drawings and the detailed description, the same referencenumerals refer to the same elements. The drawings may not be to scale,and the relative size, proportions, and depiction of elements in thedrawings may be exaggerated for clarity, illustration, and convenience.

DETAILED DESCRIPTION

This description provides a comprehensive understanding of the methods,apparatuses, and/or systems described. Modifications and equivalents ofthe methods, apparatuses, and/or systems described are apparent to oneof ordinary skill in the art. Sequences of operations are exemplary, andmay be changed as apparent to one of ordinary skill in the art, with theexception of operations necessarily occurring in a certain order.Descriptions of functions and constructions that are well known to oneof ordinary skill in the art may be omitted.

Exemplary embodiments may have different forms, and are not limited tothe examples described. However, the examples described are thorough andcomplete, and convey the full scope of the disclosure to one of ordinaryskill in the art.

A stamping method and a stamping apparatus 10 according to an embodimentwill be described with reference to FIGS. 1 to 9.

The stamping apparatus 10 of the present embodiment is employed in aprogressive stamping apparatus, which is configured to subject aplate-shaped workpiece, which is intermittently conveyed by a feeder(not shown), to multiple steps such as a piercing step and apunching-out step in a single apparatus.

As shown in FIG. 1, the stamping apparatus 10 is designed to punch out aproduct P from a workpiece 100, which is conveyed from left to right inFIG. 1. The product P of the present embodiment is a gear having teethon the outer circumference. Hereinafter, the conveying direction of theworkpiece 100 will be simply referred to as conveying direction Y, andthe upstream side and the downstream side of the conveying direction Ywill be referred to as the upstream side and the downstream side. Adirection that is orthogonal to both the conveying direction Y and thevertical direction will be referred to as a width direction.

The stamping apparatus 10 includes a protrusion providing mechanism 20,a punch-out mechanism 50, and a displacing mechanism 90. The protrusionproviding mechanism 20 is configured to provide downward protrusions 101in the workpiece 100. The punch-out mechanism 50 is provided on thedownstream side of the protrusion providing mechanism 20 and isconfigured to punch out the product P from the workpiece 100. Thedisplacing mechanism 90 is configured to displace the workpiece 100upward.

First, the protrusion providing mechanism 20 will be described.

The protrusion providing mechanism 20 includes a first lower dieassembly 30, which has two first dies 31, and a first upper die assembly40, which has two first punches 41. The conveyed workpiece 100 is placedon the first dies 31. The first punches 41 are arranged to approach andmove away from the first dies 31 in the vertical direction. The firstupper die assembly 40 is arranged to approach and move away from thefirst lower die assembly 30.

Each first punch 41 has a circular shape in the cross section orthogonalto the vertical direction.

The first upper die assembly 40 has recesses in the lower surface. Therecesses receive two first holding members 42, which hold the workpiece100 against the first dies 31. The first punches 41 are arranged to beprojected from and retracted into the lower surfaces of the firstholding members 42.

When the first punches 41 are lowered toward the first dies 31, twoprotrusions 101 each having a circular cross section are provided in theworkpiece 100. The protrusions 101 of the present embodiment are dowelsthat are protruded downward by performing half-blanking on the workpiece100. The protruding amount of the protrusions 101 from the lower surfaceof the workpiece 100 (hereinafter, simply referred to as the protrudingamount) is smaller than the thickness of the workpiece 100.

The two first dies 31 are spaced apart from each other in a widthdirection X. The two first punches 41 and the two holding members 42correspond to the two first dies 31.

Accordingly, the two protrusions 101 of the workpiece 100 are spacedapart from each other in the width direction X as shown in FIG. 2. Theworkpiece 100 has a punch-out portion 102, from which the product P willbe punched out. The protrusions 101 are provided in a part that is onthe upstream side of the punch-out portion 102 and aligned with thepunch-out portion 102. The protrusions 101 are provided at positionsthat correspond to the opposite sides of the punch-out portion 102 inthe width direction X. The protrusions 101 are provided in a feed bridgeof the workpiece 100, which connects the punch-out portion 102 to thesubsequent punch-out portion 102, which will be punched out after thefirst punch-out portion 102.

In this manner, the workpiece 100, on which the protrusions 101 areprovided, is conveyed to the punch-out mechanism 50, which is located onthe downstream side of the protrusion providing mechanism 20.

The punch-out mechanism 50 will now be described.

As shown in FIG. 1, the punch-out mechanism 50 includes a second lowerdie assembly 60, which has a second die 61, and a second upper dieassembly 70, which has a second punch 71. The workpiece 100 is placed onthe second die 61. The second punch 71 is arranged to approach and moveaway from the second die 61. The second upper die assembly 70 isarranged to approach and move away from the second lower die assembly60. The second die 61 has a gear forming portion on the innercircumferential surface, and the second punch 71 has a gear formingportion on the outer circumferential surface. The second die 61corresponds to the die of the present disclosure. The second punch 71corresponds to the punch of the present disclosure.

The second die 61 incorporates a back pressure portion 80, which isurged toward the second punch 71 to apply a back pressure to theworkpiece 100. The back pressure portion 80 includes a pushing member81, which pushes the workpiece 100 from below, and an urging portion 82,which urges the pushing member 81 upward. In a state in which thepushing member 81 is not pushed by the second punch 71, the uppersurface of the pushing member 81 and the upper surface of the second die61 are flush with each other. The pushing member 81 has a gear formingportion on the outer circumferential surface.

The urging portion 82 of the present embodiment may be a gas cylinderunit that includes, for example, a cylinder and a piston rod that isreciprocal in the cylinder.

The second upper die assembly 70 has a recess in the lower surface. Therecess receives a second holding member 72, which holds the workpiece100 against the second die 61. The second punch 71 is arranged to beprojected from and retracted into the lower surface of the secondholding member 72.

The displacing mechanism 90 will now be described.

The displacing mechanism 90 is provided in a part of the second lowerdie assembly 60 that is on the upstream side of the second die 61, andis configured to displace the workpiece 100 upward with respect to thesecond die 61. Specifically, the displacing mechanism 90 is provided inan accommodating portion 62, which is provided in the second lower dieassembly 60 and is open upward. The displacing mechanism 90 includes aclamp portion 91, which clamps the workpiece 100 in the verticaldirection, and a compression spring 92, which is provided in theaccommodating portion 62 to urge the clamp portion 91 upward.

Escape portions 63, which open upward, are provided in a part of theupper surface of the second lower die assembly 60 that is between thedisplacing mechanism 90 and the second die 61 in the conveying directionY. The escape portions 63 are designed to allow the protrusions 101 ofthe workpiece 100 to escape into when the workpiece 100 is punched out,such that the workpiece 100 is placed along the upper surface of thesecond lower die assembly 60. The depth of the escape portions 63 isgreater than the protruding amount of the protrusions 101.

An accommodating portion 73, which opens downward, is provided in a partof the lower surface of the second upper die assembly 70 that is on theupstream side of the second holding member 72. The accommodating portion73 is designed to accommodate the upper part of the clamp portion 91 ofthe displacing mechanism 90 when the second lower die assembly 60 andthe second upper die assembly 70 are clamped.

The second lower die assembly 60 has an ejection portion 64 in a partthat is on the downstream side of the second die 61. The ejectionportion 64 ejects the product P, which has been punched out by thesecond punch 71, to the outside of the second lower die assembly 60. Theejection portion 64 is a through-hole that has a diameter larger thanthe diameter of the product P and extends vertically through the secondlower die assembly 60.

The stamping method of punching out the product P from the workpiece 100using the stamping apparatus 10 will now be described.

First, as shown in FIG. 3, the workpiece 100 is conveyed to theprotrusion providing mechanism 20 by a feeder, such that the workpiece100 is placed on the first dies 31.

As shown in FIG. 4, the workpiece 100 is held between the first lowerdie assembly 30 and the first upper die assembly 40. Then, the firstpunches 41 are lowered to perform half-blanking on the workpiece 100 toprovide the protrusions 101 (protrusion providing step).

As shown in FIG. 5, the workpiece 100, on which the protrusions 101 areprovided, is conveyed to the punch-out mechanism 50. At this time, theworkpiece 100 is conveyed such that the protrusions 101 are located atpositions directly above the escape portions 63 of the second lower dieassembly 60.

Next, the second upper die assembly 70 is lowered as shown in FIG. 6, sothat the workpiece 100 is held by the second lower die assembly 60 andthe second upper die assembly 70. At this time, the upper part of theclamp portion 91 of the displacing mechanism 90 is accommodated in theaccommodating portion 73 of the second upper die assembly 70. The clampportion 91 is pushed by the second upper die assembly 70 so as to bedisplaced downward. Also, the protrusions 101 of the workpiece 100 areaccommodated in the escape portions 63 of the second lower die assembly60. Accordingly, the workpiece 100 is placed on the second die 61 whilebeing in accordance with the upper surface of the second lower dieassembly 60.

Next, the second punch 71 is lowered as shown in FIG. 7, so that thesecond die 61, the second punch 71, and the back pressure portion 80punch out the product P from the workpiece 100 (punching-out step).

Next, the second punch 71 is moved away from the second die 61 and thesecond upper die assembly 70 is lifted as shown in FIG. 8. At the sametime, the displacing mechanism 90 displaces the workpiece 100, fromwhich the product P has been punched out, upward with respect to thesecond die 61 (displacing step).

The displacing mechanism 90 displaces the workpiece 100 upward to aposition where the protrusions 101 are aligned with the product P in theconveying direction Y. The amount by which the workpiece 100 isdisplaced from the upper surface of the second lower die assembly 60 bythe displacing mechanism 90 is greater than the thickness of the productP and smaller than the sum of the thickness of the product P and theprotruding amount of the protrusions 101. In the present embodiment, theworkpiece 100 is displaced upward to a position where a small clearanceexists between the lower surface of the workpiece 100 and the uppersurface of the product P. Thus, the displacement amount is the sum ofthe thickness of the product P and the clearance.

The product P remains on the pushing member 81 in a state in which theworkpiece 100 has been displaced upward by the displacing mechanism 90.

When the workpiece 100 is conveyed further as shown in FIG. 9, theprotrusions 101 are displaced downstream in the conveying directiontogether with the workpiece 100. The protrusions 101 are caused to abutagainst the upstream end of the product P, so that the product P ispushed downstream. Accordingly, the product P is ejected to the outsidethrough the ejection portion 64 (ejection step).

As described above, the product P is produced from the workpiece 100.

The operation and advantages of the present embodiment will now bedescribed.

(1) In the punching-out step, the product P is punched out from theworkpiece 100 by the second die 61, on which the conveyed workpiece 100is placed, the second punch 71, which is arranged to approach and moveaway from the second die 61, and the back pressure portion 80, which isprovided in the second die 61 and is urged toward the second punch 71 toapply a back pressure to the workpiece 100. In the displacement step,the workpiece 100 is displaced upward with respect to the second die 61when the second punch 71 moves away from the second die 61. In theprotrusion providing step, the protrusions 101, which protrude downward,are provided prior to the punching-out step. The protrusions 101 arelocated in a part that is on the upstream side in the conveyingdirection Y of the workpiece 100 of the punch-out portion 102, fromwhich the product P will be punched out. The part is also aligned withthe punch-out portion 102. In the ejection step, the protrusions 101,which are displaced downstream in the conveying direction Y togetherwith the workpiece 100, push the product P downstream in the conveyingdirection Y, so that the product P is ejected to the outside.

With this method, the product P, which has been punched out by thesecond die 61, the second punch 71, and the back pressure portion 80,remains on the back pressure portion 80. The workpiece 100 is displacedupward with respect to the second die 61 when the second punch 71 movesaway from the second die 61. With the above-described method, theprotrusions 101, which protrude downward, are provided in the workpiece100 before the product P is punched out. Accordingly, the product P onthe back pressure portion 80 is pushed downstream in the conveyingdirection Y by the protrusions 101 as the workpiece 100 is conveyed, sothat the product P is ejected to the outside. Since the above-describedmethod ejects the product P to the outside by utilizing the conveyanceof the workpiece 100, no additional devices for ejecting the product Pto the outside are needed. The product P is ejected to the outside by asimple method.

In a case of a configuration that includes a device for ejectingproducts P to the outside, the ejection step of a product P is completedbefore the workpiece is conveyed for the punching-out step of thesubsequent product P. This extends the manufacturing time by the amountof time corresponding to the ejection step of the product P.

In this regard, the above-described method ejects the product P as theworkpiece 100 is conveyed before the subsequent product P is punchedout. This shortens the time required for the stamping process. Theproductivity of the stamping process is thus improved.

(2) Half-blanking is performed on the workpiece 100 to provide theprotrusions 101.

When, for example, magnets that are separate from the workpiece 100 areprovided as protrusions on the lower surface of the workpiece 100, anoperation for retrieving the magnets may be necessary.

In this regard, the above-described method does not require such anoperation since the protrusions 101 are provided integrally with theworkpiece 100. This improves the productivity of the stamping process.

(3) The protrusions 101 are provided at positions that correspond to theopposite sides of the punch-out portion 102 in the width direction X.

With this method, as the workpiece 100 is conveyed, the protrusions 101,which are provided at positions corresponding to the opposite sides inthe width direction X of the punch-out portion 102, push the oppositesides in the width direction X of the product P. The product P is thusejected in a reliable manner.

(4) The stamping apparatus 10 includes the punch-out mechanism 50, theprotrusion providing mechanism 20, and the displacing mechanism 90. Thepunch-out mechanism 50 includes the second die 61, on which the conveyedworkpiece 100 is placed, the second punch 71, which is arranged toapproach and move away from the second die 61, and the back pressureportion 80, which is provided in the second die 61 and is urged towardthe second punch 71 to apply a back pressure to the workpiece 100. Thepunch-out mechanism 50 is configured to punch out the product P from theworkpiece 100 by using the second die 61, the second punch 71, and theback pressure portion 80. The protrusion providing mechanism 20 isconfigured to provide the protrusions 101, which protrude downward, in apart that is located on the upstream side in the conveying direction Yof the workpiece 100 of the punch-out portion 102 of the workpiece 100,from which the product P will be punched out. The part is aligned withthe punch-out portion 102. The displacing mechanism 90 is configured todisplace the workpiece 100 to a position where the protrusions 101 andthe product P overlap with each other in the vertical direction when thesecond punch 71 moves away from the second die 61.

This configuration achieves an operational advantage similar to theabove-described operational advantage (1).

The present embodiment may be modified as follows. The presentembodiment and the following modifications can be combined as long asthe combined modifications remain technically consistent with eachother.

The ejection portion 64 may be a belt conveyor that conveys the productP to the outside.

The pushing member 81 may incorporate a lifter that is urged toward thesecond punch 71 and lifts the product P above the upper surface of thepushing member 81 in the displacement step. In this case, since thepushing member 81 is prevented from closely contacting the product P,the product P is easily ejected. At this time, the amount by which theworkpiece 100 is displaced from the upper surface of the second lowerdie assembly 60 by the displacing mechanism 90 simply needs to begreater than the sum of the thickness of the product P and theprotruding amount of the lifter from the upper surface of the secondlower die assembly 60 and smaller than the sum of the thickness of theproduct P, the protruding amount of the lifter from the upper surface ofthe second lower die assembly 60, and the protruding amount of theprotrusions 101.

Two or more displacing mechanisms 90 may be provided on the upstreamside and the downstream side of the second die 61 as necessary.

The number, the shape, and the arrangement of the protrusions 101 may bechanged in accordance with the shape of the product P as necessary. Forexample, as shown in FIG. 10, instead of multiple protrusions 101, asingle protrusion 103, which extends along the circumferential directionof the punch-out portion 102 may be provided on the upstream side of thepunch-out portion 102 and at a position aligned with the center in thewidth direction X of the punch-out portion 102.

The protrusions are not limited to the ones that are provided byperforming half-blanking on the workpiece 100. The protrusions may beprovided through burring. The protrusions may be provided on theworkpiece 100 by attaching magnets on the lower surface of the workpiece100.

The range in application of the stamping apparatus 10 is not limited tothe product P, which has gear teeth on the outer circumference. Thestamping apparatus 10 of the present embodiment can be employed inproducing products having various shapes as long as those are punchedout of a plate-shaped workpiece.

Various changes in form and details may be made to the examples abovewithout departing from the spirit and scope of the claims and theirequivalents. The examples are for the sake of description only, and notfor purposes of limitation. Descriptions of features in each example areto be considered as being applicable to similar features or aspects inother examples. Suitable results may be achieved if sequences areperformed in a different order, and/or if components in a describedsystem, architecture, device, or circuit are combined differently,and/or replaced or supplemented by other components or theirequivalents. The scope of the disclosure is not defined by the detaileddescription, but by the claims and their equivalents. All variationswithin the scope of the claims and their equivalents are included in thedisclosure.

What is claimed is:
 1. A stamping method for punching out a product froma workpiece that is conveyed intermittently, the method comprising:punching out the product from the workpiece by using a die on which theconveyed workpiece is placed, a punch that is arranged to approach andmove away from the die, and a back pressure portion that is provided inthe die and is urged toward the punch to apply a back pressure to theworkpiece; displacing the workpiece upward with respect to the die whenthe punch moves away from the die; before the product is punched out,providing a protrusion that protrudes downward and is located at a partof the workpiece, wherein the part is on an upstream side in a workpiececonveying direction of a punch-out portion, from which the product ispunched out, and is aligned with the punch-out portion; and using theprotrusion, which is displaced downstream in the conveying directiontogether with the workpiece, to push the product downstream in theconveying direction, so that the product is ejected to the outside. 2.The stamping method according to claim 1, comprising providing theprotrusion by performing half-blanking on the workpiece.
 3. The stampingmethod according to claim 1, comprising providing the protrusion at aposition that corresponds to opposite ends in a width direction of thepunch-out portion, wherein the width direction is orthogonal to both theconveying direction and a direction in which the punch approaches andmoves away from the die.
 4. A stamping apparatus for punching out aproduct from a workpiece that is conveyed intermittently, the apparatuscomprising: a punch-out mechanism that includes a die on which theconveyed workpiece is placed, a punch that is arranged to approach andmove away from the die, and a back pressure portion that is provided inthe die and is urged toward the punch to apply a back pressure to theworkpiece, wherein the punch-out mechanism is configured to punch outthe product from the workpiece by using the die, the punch, and the backpressure portion; a protrusion providing mechanism that is configured toprovide a protrusion that protrudes downward and is located at a part ofthe workpiece, wherein the part is on an upstream side in a workpiececonveying direction of a punch-out portion, from which the product ispunched out, and is aligned with the punch-out portion; and a displacingmechanism that is configured to displace the workpiece to a positionwhere the protrusion and the product are aligned with each other in theconveying direction when the punch moves away from the die.